Ruxolitinib ((3R)-3-cyclopentyl-3-[4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)pyrazol-1-yl]propanenitrile) is the first FDA approved Janus kinase (JAK) inhibitor and is the only drug currently approved for treatment of myelofibrosis. Mascarenhas, J. et al. Clin Cancer Res. 2012 Jun. 1; 18(11):3008-14. Epub 2012 Apr. 2. The compound has been shown in the clinic to effectively reduce spleen volume and improve total symptom scores in patients suffering from myelofibrosis. See, e.g., Verstovsek, S., et al. “A double-blind, placebo-controlled trial of ruxolitinib for myelofibrosis,” N. Eng. J. Med., 2012, Mar. 1:366(9):799-807, which is incorporated herein by reference in its entirety, which reports the results of a Phase 3 clinical trial (COMFORT-I Study) of ruxolitinib for myelofibrosis. See also, Harrison, C. et al., “JAK inhibition with ruxolitinib versus best available therapy for myelofibrosis,” N. Eng. J. Med., 2012, Mar. 1; 366(9):787-98 reporting Phase 3 clinical trial results of the COMFORT-II study, which is incorporated herein by reference in its entirety.
To date, all published human clinical data for ruxolitinib relate to dosing of an immediate-release formulation. However, ruxolitinib is a BCS Class I molecule with rapid oral absorption and a short half-life of about 3 hours. See, Shi et al., J. Clin. Pharmacol. 2012 June; 52(6):809-18. Epub 2011 May 20. These properties result in a high peak/trough plasma concentration ratio in human subjects leading to multiple daily doses for optimal treatment, and potentially contributing to problems with patient compliance and unwanted side effects.
Ruxolitinib therapy is often associated with the adverse events of thrombocytopenia (low platelet count) and anemia (low hemoglobin). Thrombocytopenia is dose-dependent and considered the dose-limiting toxic effect.
Accordingly, there is a need for new and improved formulations of ruxolitinib that not only mitigate adverse side-effects in patients, but still achieve therapeutic efficacy, and also facilitate administration of the drug such as by reducing the number of doses required to achieve a therapeutic effect. The sustained-release formulations provided herein help meet these and other needs.